<!DOCTYPE html>
<html>
<head>
<style>
  td {
    width: 20px;
    height: 20px;
    background-color: green;
  }
  table {
    border-collapse:separate;
    border-spacing: 0px;
  }
</style>
</head>
<body>
<table>
  <tr>
    <td></td>
    <td style="background-color: blue"></td>
  <tr>
    <td></td>
    <td></td>
  </tr>
</table>
</body>

</html>